10 Communication
Objective
Know and understand the functionality of Internet Service Providers (ISPs), the structure and security implications of a web address (URL), hyperlinks, web browsers and email, and be able to use the Internet safely and effectively.
1. Internet Service Provider (ISP)
An ISP supplies the connection that allows individuals, schools and organisations to access the Internet and related services.
| Type of ISP | Typical use‑case | Speed / latency | Security considerations |
|---|
| Dial‑up (analogue/ISDN) | Rural homes with no broadband | Up to 56 kbps, high latency | Very insecure on public lines; data can be intercepted easily. |
| DSL (digital subscriber line) | Most residential broadband | 1–20 Mbps, moderate latency | Uses telephone line – encryption (HTTPS) essential. |
| Cable broadband | Urban/suburban homes, apartments | 10–200 Mbps, low latency | Shared bandwidth – risk of traffic sniffing on the same node. |
| Fibre‑to‑the‑home (FTTH) | High‑performance homes, schools, businesses | 100 Mbps – 1 Gbps, very low latency | Most secure physical medium, still need HTTPS & firewalls. |
| Wireless (Wi‑Fi, 4G/5G mobile) | Mobile devices, hotspots, remote sites | Varies widely, can be high‑speed | Public Wi‑Fi is vulnerable to man‑in‑the‑middle attacks – use a VPN. |
| Satellite | Very remote locations, ships, aircraft | 10–50 Mbps, high latency (≈ 600 ms) | Signal can be intercepted; encryption mandatory. |
Core ISP functions
- Provide a physical/virtual connection to the Internet.
- Allocate IP addresses (static or dynamic) to customers.
- Offer value‑added services: email accounts, web hosting, cloud storage, security suites, parental controls.
- Maintain network infrastructure and enforce acceptable‑use policies.
Typical charges
- Monthly subscription (often tiered by speed or data allowance).
- One‑off installation or equipment fee.
- Charges for excess data usage or premium services.
Impact of cloud computing
- Many ISPs now bundle cloud storage (e.g., OneDrive, Google Drive) as part of the package.
- Cloud‑based applications reduce the need for powerful local hardware but increase reliance on a stable, high‑speed Internet connection.
- Data stored in the cloud is subject to the ISP’s security policies and the cloud provider’s encryption standards.
2. Email Communication
Email remains a fundamental ICT communication tool. Candidates must be able to compose, send, receive and manage email safely and professionally.
| Component | Purpose | Key points for IGCSE (AO2) |
|---|
| To | Primary recipient(s) | Enter full e‑mail address; separate multiple addresses with commas. |
| Cc (carbon copy) | Inform others without requiring action | All recipients can see who was copied. |
| Bcc (blind carbon copy) | Inform others discreetly | Recipients cannot see who was Bcc‑ed – useful for privacy. |
| Subject line | Summarise the message content | Clear, concise; helps recipients prioritise. |
| Body | Main message | Follow netiquette: greeting, clear paragraphs, sign‑off. |
| Attachments | Send files (documents, images, spreadsheets) | Check file‑size limits (commonly 10–25 MB); scan for viruses. |
Netiquette (email etiquette)
- Use a professional address (e.g., name@school.edu).
- Write a relevant subject line.
- Keep the tone polite and concise.
- Avoid ALL CAPS – it is interpreted as shouting.
- Proofread before sending.
- Do not forward chain letters or unverified information.
Security & safety
- Recognise phishing – unexpected requests for passwords or personal data.
- Never open attachments from unknown senders; use built‑in virus scanning.
- Use strong passwords and enable two‑factor authentication where possible.
- Spam filtering: mark unwanted mail as junk to improve the filter.
- Compress large files before attaching and be aware of size limits.
3. Effective Use of the Internet
3.1 Key concepts
- Internet vs. Intranet vs. Extranet – The Internet is a global public network; an intranet is a private network within an organisation; an extranet extends an intranet to selected external users (e.g., partners).
- Cloud computing – Delivery of services (storage, applications, processing) over the Internet. Examples: Google Docs, Microsoft 365, AWS.
- World Wide Web (WWW) – System of interlinked hypertext documents accessed via browsers.
- Blogs, Wikis and Social‑Networking Sites – Platforms for publishing, collaborative editing and social interaction. Examples: WordPress (blog), Wikipedia (wiki), Facebook/Instagram (social networking).
3.2 Internet protocols (beyond HTTP/HTTPS)
| Protocol | Full name | Typical use | Port (default) |
|---|
| FTP | File Transfer Protocol | Uploading/downloading files to/from a server | 21 (control), 20 (data) |
| SMTP | Simple Mail Transfer Protocol | Sending e‑mail from client to server | 25 (or 587 for submission) |
| POP3 | Post Office Protocol 3 | Retrieving e‑mail from server (download & delete) | 110 (or 995 for POP3 + SSL) |
| IMAP | Internet Message Access Protocol | Retrieving e‑mail while keeping it on the server | 143 (or 993 for IMAP + SSL) |
3.3 Searching the Web
- Choose specific keywords; use quotation marks for exact phrases.
- Use Boolean operators:
AND, OR, NOT. - Advanced operators (Google):
site:edu to limit to educational domains, filetype:pdf for PDFs. - Evaluate results (see 3.4).
3.4 Evaluating online information
| Criterion | What to check | Why it matters |
|---|
| Authority | Who is the author? Is the site run by a recognised organisation? | Establishes credibility. |
| Accuracy | Are facts supported by evidence or references? | Prevents the spread of misinformation. |
| Currency | When was the information published or last updated? | Ensures relevance, especially for fast‑changing topics. |
| Purpose / Bias | Is the page trying to inform, persuade, sell, or entertain? | Helps detect hidden agendas. |
| Domain suffix | .gov, .edu, .org often indicate trustworthy sources; commercial sites (.com) may have commercial bias. | Quick initial cue about reliability. |
3.5 Risks & safe‑use (e‑Safety)
- Malware & viruses – Keep anti‑virus software up to date; avoid downloading from untrusted sites.
- Phishing & social engineering – Verify the sender’s address, never click suspicious links.
- Data privacy – Share personal data only on secure (HTTPS) sites; read privacy policies.
- Cyberbullying & online behaviour – Treat others with respect; report abusive content.
- Public Wi‑Fi – Use a VPN; avoid accessing sensitive accounts.
- Password hygiene – Use long, unique passwords; enable two‑factor authentication.
- Safe browsing tools – Enable browser’s built‑in phishing & malware protection; consider reputable extensions.
- Reporting – Know how to report inappropriate content to teachers, parents or platform moderators.
4. Structure of a Web Address (URL)
A Uniform Resource Locator (URL) tells a browser exactly where to find a resource on the Internet.
| Component | Example | Purpose | Security / privacy impact |
|---|
| Protocol | https:// | Defines the communication method (HTTP, HTTPS, FTP, etc.) | HTTPS encrypts data; HTTP transmits in clear text. |
| Subdomain | www. | Optional prefix; can indicate a specific service (mail., blog., shop.) | Generally not a security risk, but suspicious subdomains may be spoofed. |
| Domain name | example | Human‑readable name registered with a registrar. | Domain reputation influences trust (e.g., known phishing domains). |
| Top‑level domain (TLD) | .com | Shows category or country (.org, .gov, .uk, .co.nz) | Country‑code TLDs sometimes indicate localisation of data storage. |
| Port (optional) | :443 | Specifies a network port; defaults are assumed (80 for HTTP, 443 for HTTPS). | Non‑standard ports may be blocked by firewalls; can hint at specialised services. |
| Path | /folder/page.html | Locates a specific file or resource on the server. | Exposes directory structure – avoid revealing sensitive folders. |
| Query string (optional) | ?id=25&type=student | Passes parameters to server‑side scripts. | Values are visible in the address bar – never transmit passwords or personal data here. |
| Fragment (optional) | #section2 | Jumps to a specific part of the page after it loads. | Never sent to the server; purely client‑side. |
How a browser uses a URL
- Read the protocol and open a socket on the appropriate port.
- Resolve the domain name to an IP address via DNS.
- Establish a TCP (or TLS for HTTPS) connection.
- Send an HTTP request that includes the path and any query string.
- Receive the server’s response (HTML, CSS, JavaScript, images, etc.).
- Render the content; if a fragment identifier is present, scroll to that section.
5. Hyperlink
A hyperlink connects one resource to another. In HTML the <a> (anchor) element creates a link.
<a href="https://www.example.com/page.html" target="_blank" title="Visit Example">Visit Example</a>
- href – Destination URL (mandatory).
- target – Where to open the link:
_self – same tab (default)._blank – new tab or window.parent / top – for frames.
- title – Optional tooltip displayed on hover.
Types of links
- External link – points to a different domain.
- Internal link – points to another page within the same site.
- Anchor link – uses a fragment identifier to jump to a section on the same page (e.g.,
#chapter3). - Download link – often includes the
download attribute to force saving (e.g., <a href="file.pdf" download>Download PDF</a>).
6. Web Browser
A web browser interprets web languages and presents the requested resource to the user.
| Function | Description | Security feature |
|---|
| Render HTML & CSS | Builds the visual layout from markup and style sheets. | Sandboxing prevents malicious code from accessing local files. |
| Execute JavaScript | Enables interactivity, form validation, dynamic content. | Same‑origin policy restricts scripts to their own domain; Content‑Security‑Policy (CSP) can further limit actions. |
| Manage sessions | Stores cookies, local storage, cache, browsing history. | Secure cookies (flag = Secure) are sent only over HTTPS; HttpOnly flag prevents JavaScript access. |
| Implement security protocols | Supports HTTPS, validates SSL/TLS certificates, warns about expired or mismatched certificates. | Mixed‑content warnings block insecure HTTP resources on an HTTPS page. |
| Navigation controls | Address bar, back/forward buttons, refresh, bookmarks, tabs. | Address‑bar phishing detection (e.g., highlighting mismatched domains). |
| Privacy tools | Private/incognito mode, tracking‑protection extensions. | Prevents storage of cookies and history for the session. |
Typical browser workflow (request → render)
- User enters a URL or clicks a hyperlink.
- Browser performs DNS lookup to obtain the server’s IP address.
- Establishes a TCP/TLS connection.
- Sends an HTTP request (GET/POST) including any query string.
- Receives the response (HTML, CSS, JS, images, etc.).
- Parses HTML → builds the Document Object Model (DOM).
- Applies CSS → creates the Render Tree.
- Executes JavaScript → may modify the DOM.
- Paints pixels on the screen; handles any fragment identifier navigation.
7. Security of Data (Protection of Data)
- Encryption – Converts data into a coded form; HTTPS uses TLS encryption for web traffic.
- Firewalls – Hardware or software that blocks unauthorised inbound/outbound traffic.
- SSL/TLS certificates – Verify the identity of a website and enable encrypted connections.
- Digital certificates – Issued by Certificate Authorities; used for code signing and secure email (S/MIME).
- Biometric security – Fingerprint, facial recognition, iris scan – increasingly used on mobile devices.
- Passwords & authentication – Strong, unique passwords; two‑factor authentication (2FA) adds a second verification step.
- Backup & recovery – Regularly back up important files to external drives or cloud services; test restoration procedures.
8. Audience & Copyright
- Audience awareness – Choose language, tone and media appropriate to the intended readers (e.g., formal email to a teacher, informal chat with friends).
- Copyright basics – Original works are protected automatically; you must obtain permission or use royalty‑free/Creative‑Commons resources for images, music, video, and text.
- Plagiarism – Presenting someone else’s work as your own is prohibited; always cite sources.
- Software licences – Understand differences between proprietary, open‑source and free‑to‑use licences.
9. File Management (supporting communication)
- Naming conventions – Use clear, consistent names (e.g.,
ReportYear2025V1.docx); avoid spaces and special characters. - Folder hierarchy – Organise files in logical folders (e.g.,
Documents/Science/Reports/2025/). - File‑type selection – Choose appropriate formats: .docx for editable text, .pdf for fixed layout, .jpg/.png for images, .csv for data tables.
- Version control – Keep older versions (V1, V2…) or use cloud‑based version history.
- Backup strategy – At least 3‑2‑1 rule: three copies, on two different media, with one off‑site (cloud).
10. Summary Checklist
- Explain the role of an ISP and differentiate between its main types, including speed, latency and security aspects.
- Identify the parts of a URL, describe their purpose, and discuss any security or privacy implications.
- Write a correct HTML hyperlink using the
<a> tag and choose appropriate attributes (href, target, title, download). - Describe how a web browser retrieves a page, renders it, and enforces security (HTTPS, same‑origin policy, CSP).
- Compose a professional email, applying correct components, netiquette and security measures (phishing awareness, strong passwords, 2FA).
- Distinguish between Internet, Intranet and Extranet and give an example of each.
- Explain basic e‑safety practices: safe browsing, use of VPN on public Wi‑Fi, reporting cyberbullying, protecting personal data.
- Outline key data‑protection methods: encryption, firewalls, SSL/TLS certificates, passwords and backups.
- State the importance of audience awareness and copyright when creating digital content.
- Apply good file‑management techniques to organise, name and back up documents used for communication.